> Probably, the natural-sounding English for this would be to ignore the kohai-sempai relationship, the same way we just say brother and ignore the otouto and oniisan difference.
>
> Or you could be more exact, like this.
> Tom and I went to the same high school. He was a year below me.

こういうのは2つ訳をつけるのがいいんでしょうね。
後輩というと、別に1つ下とは限らないのですが、それを表せる言い方ってありますか？

> >別に1つ下とは限らない
>
> That's what I meant. You would need to be "more exact" in English to sound natural.
> Or you need to be less exact, "Tom and I went to the same high school."
>
> Tom and I went to the same high school. He's younger than I am.
> .. This would be OK, but this can mean you're still in the same class.
>
>
> Traditionally, dictionaries have used phrases like "Tom's my junior," but that doesn't quite sound right, either.

I see. Then I'll add three translations.

(Since these kinds of comments are very interesting and valuable, I strongly hope you won't delete them.)

Actually one more. Tom and "I" could still be high school students.

Would you prefer "below"/"above" to "behind"/"ahead of", which some Japanese-English dictionaries use?

Didn't stop him from deleting, apparently. -_-

> I usually say below, but either is OK.
>
> One more possibility is that you have already graduated from high school and Tom hasn't.
>
> When speaking English with friends I grew up with, we just use the Japanese words kohai and sempai when that difference is important. If there is someone in the conversation who doesn't understand the concept, he's just say "What does kohai mean?" and we'd explain it.


> I'm not sure these would be considered good translations.
> However, it is how we would naturally say this kind of sentence in English.